15,975 research outputs found
Modeling of open quantum devices within the closed-system paradigm
We present an alternative simulation strategy for the study of nonequilibrium carrier dynamics in quantum devices with open boundaries. We propose to replace the usual modeling of open quantum systems based on phenomenological injection/loss rates with a kinetic description of the system-reservoir thermalization process. In this simulation scheme the partial carrier thermalization induced by the device spatial boundaries is treated within the standard Boltzmann-transport approach via an effective scattering mechanism between the highly nonthermal device electrons and the thermal carrier distribution of the reservoir. Applications to state-of-the-art semiconductor nanostructures are discussed. Finally, the proposed approach is extended to the quantum-transport regime; to this end, we introduce an effective Liouville superoperator, able to describe the effect of the device spatial boundaries on the time evolution of the single-particle density matrix
Recent progress in open quantum systems: Non-Gaussian noise and decoherence in fermionic systems
We review our recent contributions to two topics that have become of interest
in the field of open, dissipative quantum systems: non-Gaussian noise and
decoherence in fermionic systems. Decoherence by non-Gaussian noise, i.e. by an
environment that cannot be approximated as a bath of harmonic oscillators, is
important in nanostructures (e.g. qubits) where there might be strong coupling
to a small number of fluctuators. We first revisit the pedagogical example of
dephasing by classical telegraph noise. Then we address two models where the
quantum nature of the noise becomes essential: "quantum telegraph noise" and
dephasing by electronic shot noise. In fermionic systems, many-body aspects and
the Pauli principle have to be taken care of when describing the loss of phase
coherence. This is relevant in electronic quantum transport through metallic
and semiconducting structures. Specifically, we recount our recent results
regarding dephasing in a chiral interacting electron liquid, as it is realized
in the electronic Mach-Zehnder interferometer. This model can be solved
employing the technique of bosonization as well as a physically transparent
semiclassical method.Comment: Proceedings of Ustron 2008 conference, 6 pages, 3 figure
Microscopic theory of quantum-transport phenomena in mesoscopic systems: A Monte Carlo approach
A theoretical investigation of quantum-transport phenomena in mesoscopic
systems is presented. In particular, a generalization to ``open systems'' of
the well-known semiconductor Bloch equations is proposed. The presence of
spatial boundary conditions manifest itself through self-energy corrections and
additional source terms in the kinetic equations, whose form is suitable for a
solution via a generalized Monte Carlo simulation. The proposed approach is
applied to the study of quantum-transport phenomena in double-barrier
structures as well as in superlattices, showing a strong interplay between
phase coherence and relaxation.Comment: to appear in Phys. Rev. Let
Resonant optical electron transfer in one-dimensional multiwell structures
We consider coherent single-electron dynamics in the one-dimensional
nanostructure under resonant electromagnetic pulse. The structure is composed
of two deep quantum wells positioned at the edges of structure and separated by
a sequence of shallow internal wells. We show that complete electron transfer
between the states localized in the edge wells through one of excited
delocalized states can take place at discrete set of times provided that the
pulse frequency matches one of resonant transition frequencies. The transfer
time varies from several tens to several hundreds of picoseconds and depends on
the structure and pulse parameters. The results obtained in this paper can be
applied to the developments of the quantum networks used in quantum
communications and/or quantum information processing.Comment: 25 pages,16 figure
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